The present invention relates generally to pressure activated switches, and more particularly, the present invention is directed to an electrical switch mat.
Various types of electrical switch mats are known in the art. Electrical switch mats have been designed for use in many different applications including use in floor mats for security, safety or other purposes to detect movement of objects or pedestrian traffic thereover. Another application of switch mats includes the placement in passenger seats for actuation when a person sits in the seat; and yet another application involves placement of a pressure switch in the street surface for the detection of traffic flow.
Electrical switches have been incorporated within several types of mats in order to protect the switches from wear and other potentially adverse effects such as moisture. Included among such mat switches are those shown in U.S. Pat. No. 2,938,977 to Koenig, U.S. Pat. No. 3,243,540 to Miller, U.S. Pat. No. 3,283,096 to Horton (which corresponds to Canadian patent 787,520), U.S. Pat. No. 4,497,989 to Miller, and U.S. Pat. Nos. 5,001,310, and 5,142,109, each issued to O'Meara, Jr. et al.
U.S. Pat. No. 2,938,977 to Koenig discloses an electric switching mat having a bottom sheet of insulating material, a plurality of upper and lower contact strips separated by insulating strips, and an upper sheet of insulating material placed over the strips thereby sandwiching the strips between the upper and lower sheets.
U.S. Pat. No. 3,243,540, to Miller discloses an electric mat switch incorporating compressible protective layers made of foam rubber or the like.
U.S. Pat. No. 3,283,096, to Horton discloses a mat switch having a single sealed envelope for the switch element. The membranes of the switch element are themselves relatively thick members made from glass fiber-reinforced synthetic polymer in order to prevent buckling and shorting of the contact elements.
U.S. Pat. No. 3,722,086 to Wikkerink, et al. discloses a process for making floor mat switches made of two contact plates formed of sheets of slight gauge spring steel which are spaced apart by a plurality of dielectric pads. Additionally, a band of dielectric material is positioned between the peripheral edges of the contact plates.
U.S. Pat. No. 4,497,989, to Miller discloses an electric mat switch wherein two conductor layers are separated by a separator layer of PVC foam. The electric mat switch also comprises a top outer layer and a separate moisture layer formed of PCV, an upper bulking layer formed of fiberglass fabric, all of which are disposed above the conductor layers. Below the conductor layers are a corresponding lower bulking layer formed of fiberglass fabric, a lower moisture layer, and a lower outer layer.
U.S. Pat. Nos. 5,001,310 and 5,142,109, each issued to O'Meara, Jr. et al., show a pressure-actuated electrical switching mat having a moisture resistant switching chamber. This switching chamber is protected by a puncture resistant protective layer.
Electrical ribbon switches have been incorporated into numerous designs for electrical switch mats. U.S. Pat. Nos. Re. 24,541, 2,896,042, 3,412,224, 3,694,600, and 3,710,054, each to Koenig show various constructions of open pressure sensitive ribbon switches, the disclosure of which are incorporated herein by reference. U.S. Pat. No. 3,717,735 to Koenig and U.S. Pat. No. 4,987,277 to Duhon illustrate various constructions for a closed pressure sensitive ribbon switches, the disclosure of which are incorporated herein by reference. Both the open and closed pressure sensitive ribbon switches generally include a pair of either spaced or closed conductors respectively supported in an insulative jacket. Generally, relatively light pressure on the jacket will close the space in an open switch and open the conductors in a close switch thereby activating the switch.
In connection with the traditional style electrical switch mats described above, U.S. Pat. No. 5,510,586 to Hacking discloses a switch joint for use between a pair of electrical switch mats. The switch joint uses an electrical ribbon switch to provide pressure-sensitive continuity between a pair of electrical switch mats.
Electrical switch mats as described above have been useful, however, they are generally not field repairable allowing for the replacement of worn or damaged parts. Further, a problem associated with the traditional style electric mat is that when a pair of electrical switch mats are used next to each other there is an inactive zone unless a switch joint such as, for example, the apparatus disclosed in U.S. Pat. No. 5,510,586 to Hacking is used.